Hydrodynamic coupling device

ABSTRACT

A hydrodynamic coupling device, in particular, a torque converter or fluid clutch comprises a housing assembly ( 12 ), a turbine wheel ( 32 ) provided inside the housing assembly ( 12 ), a torque converter lockup clutch assembly ( 56 ), with which a torque transmission connection can be established as desired between the turbine wheel ( 32 ) and the housing assembly ( 12 ), whereby the torque converter lockup clutch assembly ( 56 ) comprises: at least one essentially annular friction element ( 66, 68 ), which is connected to the turbine wheel ( 32 ) for mutually rotating about a rotational axis (A), and; a pressing element ( 58 ), which is connected to the housing assembly ( 12 ) for mutually rotating about the rotational axis (A), and the at least one friction element ( 66, 68 ) can be subjected to the action of said pressing element in order to establish the torque transmission connection between the turbine wheel ( 32 ) and the housing assembly ( 12 ). The invention provides that a ratio of a flow outside diameter (a) in the area of the turbine wheel ( 32 ) to a friction outside diameter (b) of the at least one friction element ( 66, 68 ) ranges from 1.30 to 1.80, preferably from 1.35 to 1.70 and/or that a ratio of a friction outside diameter (b) of the at least one friction element ( 66, 68 ) to a friction inside diameter (c) of the at least one friction element ( 66, 68 ) ranges from 1.10 to 1.25, preferably from 1.15 to 1.20.

TECHNICAL FIELD

[0001] The present invention is directed to a hydrodynamic clutchdevice, particularly a torque converter or fluid clutch, comprising ahousing arrangement, a turbine wheel provided in the housingarrangement, a lockup clutch arrangement by means of which a torquetransmission connection can be produced selectively between the turbinewheel and the housing arrangement, the lockup clutch arrangementcomprising at least one substantially annular friction element which isconnected to the turbine wheel for rotating jointly about an axis ofrotation and a pressing element which is connected to the housingarrangement for rotating jointly about the axis of rotation and by meansof which the at least one friction element can be acted upon to producethe torque transmission connection between turbine wheel and housingarrangement.

PRIOR ART

[0002] In hydrodynamic clutch devices of the type mentioned above,particularly in a state in which at least some of the torque to betransmitted along an output powertrain is conducted from the housingarrangement to the turbine wheel via the lockup clutch arrangement,torsional vibrations occurring in the drive system can be contained inthat a certain slip is permitted in the lockup clutch arrangement, sothat torque peaks can lead to a relative rotation between the housingarrangement and the turbine wheel. This results in a comparatively largeload on the structural component parts or surface regions coming intofrictional contact with one another in the area of the lockup clutcharrangement, since the power losses which occur at least with greatertorque fluctuations and which are contained by the slip are convertedinto heat.

[0003] In order to meet the demands of increasing possible power lossesin the area of the lockup clutch arrangement, systems are known likethose, for example, disclosed in WO 00/03158. In the hydrodynamic torqueconverter known from this reference, the lockup clutch arrangement hastwo friction elements coupled with the turbine wheel such that theyrotate jointly, an intermediate friction element which is coupled withthe housing arrangement for joint rotation being positionedtherebetween. The individual friction surface regions are made tointeract with each other by the clutch pistons acting as pressingelement. By providing a plurality of radially offset friction surfacepairs which can be made to interact with one another, the entireavailable friction surface can be appreciably enlarged without asubstantial space requirement with the result that the power lossoccurring in slip operation is also distributed over a larger surfaceand can accordingly be carried off in an improved, faster manner.

OBJECT OF THE INVENTION

[0004] It is the object of the present invention to further develop ahydrodynamic clutch device of the type mentioned in the beginning insuch a way that it has improved performance with respect to the demandsarising during operation, particularly the demands occurring in slipoperation.

DESCRIPTION OF THE INVENTION

[0005] According to the present invention, this object is met by ahydrodynamic clutch device, particularly a torque converter or fluidclutch, comprising a housing arrangement, a turbine wheel provided inthe housing arrangement, a lockup clutch arrangement by means of which atorque transmission connection can be produced selectively between theturbine wheel and the housing arrangement, the lockup clutch arrangementcomprising at least one substantially annular friction element which isconnected to the turbine wheel for rotating jointly about an axis ofrotation and a pressing element which is connected to the housingarrangement for rotating jointly about the axis of rotation and by meansof which the at least one friction element can be acted upon to producethe torque transmission connection between turbine wheel and housingarrangement.

[0006] It is further provided according to the invention that a ratio ofa flow outer diameter in the area of the turbine wheel to a frictionouter diameter of the at least one friction element ranges between 1.30and 1.80, preferably between 1.35 and 1.70 and/or that a ratio of afriction outer diameter of the at least one friction element to afriction inner diameter of the at least one friction element rangesbetween 1.10 and 1.25, preferably between 1.15 and 1.20.

[0007] By means of the first step according to the invention, namely,preparing a determined ratio between the flow outer diameter and thefriction outer diameter of the at least one friction element, anappreciably more favorable distribution of mass is obtained, whichresults in a lower mass moment of inertia. The second step according tothe invention leads to a lockup clutch arrangement with larger frictionsurface regions, so that the occurring power losses can be betterabsorbed and transmitted to surrounding components or component groups.

[0008] It is preferably provided in the hydrodynamic clutch deviceaccording to the invention that, in an area radially outside of thelockup clutch arrangement, the housing arrangement has a shape that isadapted to the outer circumferential contour of the lockup clutcharrangement and to the outer circumferential contour of the turbinewheel. As a result of this step, the housing arrangement has greaterrigidity particularly in its area which is also provided for the lockupclutch arrangement and for the action of the latter. This causes anappreciably smaller bulging or inflation of the converter housing underthe fluid pressure prevailing in the interior of the converter housing,so that even relatively wide friction surface regions—measured in radialdirection—can not lead to edge loading of friction linings or the likeinduced by bulging. For example, it can be provided for this purposethat the housing arrangement is constructed in a first housing portionso as to surround the lockup clutch arrangement substantiallycylindrically and has, in a second housing portion adjoining the firsthousing portion, a shape which is curved in direction of the axis ofrotation and extends along the outer circumferential area of the turbinewheel.

[0009] According to another advantageous aspect of the presentinvention, it can be provided that the at least one friction element isconnected to the turbine wheel so as to be essentially rigid againstrotation by a driving element. Therefore, it is no longer necessary tocouple the at least one friction element to the turbine wheel via atorsional vibration damper or the like with the result that theinstallation space can be used more efficiently and, in particular, theshape of the housing arrangement mentioned above can be provided in asimple manner.

[0010] The efficient use of construction space can be further assistedin the hydrodynamic clutch device according to the invention in that thepressing element is connected to the housing arrangement so as to rotatejointly by a driving arrangement which is arranged essentially in theaxial area between the pressing element and the turbine wheel.

[0011] As was already stated, it is advantageous for increasing theeffective friction surface region when a plurality of friction elementsare provided, wherein an intermediate friction element connected to thehousing arrangement for joint rotation is arranged between two frictionelements in each instance.

[0012] In order to further optimize the mass moment of inertia existingin the hydrodynamic clutch device according to the invention, asubstantially annular first coupling element can be provided which isconnected in its radial inner area to an outer side of the housingarrangement, preferably by laser welding, and is constructed in itsradial outer area for coupling with a second coupling element which isfixedly connected or connectable to a drive shaft.

[0013] A construction of a hydrodynamic clutch device which isparticularly simple to realize and which operates on the principle of adual-line system can be achieved in that an interior space of thehousing arrangement is divided by a pressing element into a first spacein which the turbine wheel is arranged and a second space, and in thatwork fluid can be introduced into the first space and work fluid can beconducted out of the second space, or vice versa, for an exchange ofwork fluid that is provided in the interior. In order to enable anexchange of fluid in a system of the type mentioned above also duringthe locked up state, it is proposed that at least one fluidthrough-opening is provided in the pressing element to enable anexchange of fluid between the first space and the second space. Further,to enable a fluid cooling in the slip state, it is further suggestedthat a flow channel arrangement which is preferably arc-shaped isprovided in a friction surface region of the at least one frictionelement. This flow channel arrangement is then preferably open towardthe two spaces, so that a passage of fluid through the flow channelarrangement will take place due to the pressure difference between thetwo spaces which exists in any case in the locked up state, and the heatenergy occurring in this spatial region can be carried off.

[0014] The present invention will be described in the following withreference to the accompanying drawings.

[0015]FIG. 1 shows a partial longitudinal section through a hydrodynamicclutch device according to the invention;

[0016]FIG. 2 shows a modified embodiment form of the hydrodynamic clutchdevice shown in FIG. 1.

[0017] The hydrodynamic torque converter 10 shown in FIG. 1 comprises ahousing arrangement which is designated in general by 12. This housingarrangement 12 in turn substantially comprises a housing cover 14 whichis fixedly connected in its radial outer area, for example, by welding,to an impeller wheel shell 16. The impeller wheel shell 16 is fixedlyconnected on the radial inside to an impeller wheel hub 18. At its innerside facing the interior space 20, the impeller wheel shell 16 carries aplurality of impeller wheel blades 22 arranged successively incircumferential direction. Together with the impeller wheel hub 18 andthe impeller wheel blades 22, the impeller wheel shell 16 substantiallyforms an impeller wheel 24. In its radial inner area, the housing cover14 has a central opening 26 in which a housing hub 28 is inserted. Inits area located near the axis of rotation A, the housing hub 28 carriesa centering pin 30 which is inserted into a corresponding centeringrecess of a drive shaft, not shown, e.g., a crankshaft, for aligning theaxis of rotation A of the torque converter 10 with respect to the axisof rotation of the drive shaft. Further, a turbine wheel which isdesignated generally by 32 is arranged in the interior 20 of the torqueconverter 10. This turbine wheel 32 comprises, in the radial outer area,a turbine wheel shell 34 which carries a plurality of turbine wheelblades 36 at its side facing the impeller wheel 24. On the radialinside, the turbine wheel shell 34 is fixedly connected to a turbinewheel hub 38, for example, by welding. The turbine wheel hub 38 in turncan be connected to a driven shaft, for example, a transmission inputshaft, so as to be fixed with respect to rotation relative to it.

[0018] A stator wheel 40 is provided axially between the impeller wheel24 and the turbine wheel 32. The stator wheel 40 comprises a pluralityof stator wheel blades 44 on a stator wheel ring 42, these stator wheelblades 44 being positioned between the radial inner end regions of theimpeller wheel blades 22 and the turbine wheel blades 36. The statorwheel ring 42 is supported via a freewheel arrangement, designatedgenerally by 46, on a supporting element, for example, a supportinghollow shaft, not shown, so as to be rotatable in one direction aroundthe axis of rotation A and blocked against rotation in the otherdirection. In axial direction, the stator wheel 40 is supported axiallyby two bearing arrangements 50, 52 with respect to the impeller wheel 24on one side and with respect to the turbine wheel 32 on the other side.The turbine wheel 32 is supported in turn axially at the housing hub 28by a bearing 54.

[0019] A lockup clutch arrangement, designated generally by 56, isprovided to produce a direct mechanical torque transmission connectionbetween the turbine wheel 32 and the housing arrangement 12. This lockupclutch arrangement 56 comprises a clutch piston 58 which is held so asto be axially displaceable by a radial inner cylindrical portion on anouter circumferential surface of the housing hub 28 with theintermediary of a sealing element 60. A ring-shaped or star-shapeddriving element 62 is fastened, for example, by laser welding, to an endface of the housing hub 28 facing the turbine wheel 32. This drivingelement 62 has, in its radial outer area, an elastic arrangement, forexample, one or more leaf spring elements 64 by which the piston 58 isheld so as to be axially movable with respect to the driving element 62but not rotatable in circumferential direction around the axis ofrotation A.

[0020] The lockup clutch arrangement 56 further comprises two plateelements or friction elements 66, 68 which carry friction linings 70,72, 74, 76 at their respective axial end faces. In their radial outerarea, respective carrier elements 77, 78 of the friction elements 66, 68have a toothing arrangement in driving engagement with a correspondingtoothing arrangement of an annular driving element 80. This drivingelement 80 is fastened to a surface region of the turbine wheel shell 34again by laser welding, for example. Accordingly, a connection which isrigid with respect to rotation is produced between the friction elements66, 68 and the turbine wheel 32.

[0021] Located axially between the two friction elements 66, 68 is anintermediate friction element 82 having a toothing configuration in itsradial outer area, which toothing configuration engages with acorresponding toothing configuration of a driving element 84 fastened tothe housing cover 14.

[0022] In order to produce the locked up state, the fluid pressure in aspace 86 in the housing arrangement 12, in which space 86 the turbinewheel 32 is also arranged, is increased with respect to the fluidpressure prevailing in a space 88. This space 88 lies essentiallybetween the piston 58 and the housing cover 14, i.e., the interior 20 ofthe housing arrangement 12 is essentially divided into these two spaces86 and 88 by the piston 58. In order to increase the fluid pressure inthe space 86, fluid can be introduced via a through-opening arrangement90 in the area of the stator wheel 40 by the fluid pump, not shown, viaan intermediate space formed, for example, between the driven shaft, notshown, and the supporting hollow shaft. When not in the locked up state,the fluid can enter the space 88 from space 86 by flowing around thefriction elements 66, 68 and can flow to a central through-opening inthe driven shaft via through-openings 92 which are provided in thehousing hub 28 and extend radially inward and then to a fluid reservoir.In order to make possible an exchange of fluid also in the locked upstate in which the clutch piston 58 is pressed against the frictionelement 68 and, basically in the radial outer area, the space 88 issealed with respect to space 86 so as to be tight against fluid by meansof the surface regions in frictional contact with one another, at leastone through-opening 94 is provided in the clutch piston 58, whichthrough-opening 94 is located radially inside of an annular surfaceregion thereof which frictionally cooperates with the friction lining 76of the friction element 68. Further, the friction linings 70, 72, 74, 76have lining grooves, for example, with a curved contour, which opentoward the space 86 in the radial outer area and open toward space 88 inthe radial inner area, so that the occurring friction heat can be guidedoff also in the locked up state, particularly in the slip state, byfluid flowing through in the region of the friction linings 70, 72, 74,76.

[0023] As was already stated, it is advantageous, for example, in orderto achieve a torsional vibration damping, to operate the lockup clutcharrangement 56 in a slip state so that a relative rotation between thehousing arrangement 12 and the turbine wheel 32 is possible at leastwhen torque peaks occur. By providing a plurality of friction surfacepairs which engage with one another frictionally, the entire availablefriction surface is increased, with the result that the occurring loadis distributed over a larger surface region and, therefore, thedissipation of heat can also be improved. In order to optimize orminimize the total mass moment of inertia, the friction outer diameter bof the friction linings 70, 72, 74, 76 is kept comparatively small.Accordingly, a ratio of the fluid flow outer diameter a whichapproximately corresponds to the outer diameter of the turbine wheel 32with respect to the friction outer diameter b is preferably in the rangeof 1.35 to 1.70. This means that the flow outer diameter a isappreciably greater than the friction outer diameter b.

[0024] Further, the value of the ratio between the friction outerdiameter b and the friction inner diameter c of the friction linings 70,72, 74, 76 is advantageously in the range of 1.15 to 1.20. This resultsin a comparatively large radial extension of the annular frictionlinings. Further, in order for this to be realized without difficulty inoperation, the housing 12 of the hydrodynamic torque converter 10 isconstructed in such a way that directly adjoining the radial outer areaof the lockup clutch arrangement 56, i.e., the radial outer area of thefriction elements 66, 68, in a first housing portion 96, the housingcover 14 extends approximately cylindrically or axially and thereforeruns close to the outer circumferential contour of the lockup clutcharrangement 56, which means that a stiffening of the housing arrangement12 is provided directly adjoining the lockup clutch arrangement 56 inthe radial outer area by means of the bent contour of the housing cover14. In the area near the turbine wheel 32 and turbine wheel shell 34,the housing cover 14 is curved in an arc shape in axial direction in asecond housing portion 98 which adjoins the first housing portion 96 orpasses into the latter and its shape is therefore adapted to the outercontour of the turbine wheel 32. This leads to a further stiffening ofthe housing arrangement 12 with the result that a bulging or inflationof the housing 12 which leads to edge loading in the area of thefriction lining 70 in which the latter contacts a substantially radiallyextending portion 100 of the housing arrangement 12 can be prevented dueto the work fluid which is provided under pressure in the interior 20.

[0025] This structure of the torque converter 10 according to theinvention is made possible essentially in that the friction elements 66,68 are connected to the turbine wheel shell 34 without providing atorsional vibration damper in its radial outer area.

[0026] Of course, more than two friction elements 66, 68, for example,three friction elements, and, in this case, a correspondingly largerquantity of intermediate friction elements 82 can be used in the torqueconverter 10 according to the invention. Also, the basic concept can beused with only one friction element. By combining the total frictionsurface—which is increased nevertheless—with a torque converterprinciple of the dual-line system in which the work fluid is introducedinto the space 86 and guided out again via the space 88, a veryfunctional high-power converter is obtained in which torque fluctuationscan be contained in particular through the slip operation of the lockupclutch arrangement 56.

[0027] Another advantage of the torque converter 10 according to theinvention consists in the way that the torque converter 10 is connectedto a drive shaft. FIG. 1 shows an annular coupling element 102 which isbent in axial direction and formed of sheet metal, for example. In itsradial inner area, this coupling element 102 is preferably arranged atthe housing cover 14 by laser welding. Laser welding is advantageous inthis case because it is carried out in the area in which the housingcover 14 provides a friction surface at its inner surface and thereforeany deformation would be disadvantageous when carrying out a weldingprocess. In its radial outer area, the coupling element has a pluralityof nut elements 104 or the like. Screw bolts, or the like, connectingthe coupling element 102 with a flexplate or the like can be screwedinto these nut elements 104. This flex plate can then be screwed to acrankshaft flange or the like by its radial inner area in a manner knownper se. This economizes on weight in the radial outer area of the torqueconverter 10 and accordingly further reduces the mass moment of inertia.

[0028] A construction such as that shown in FIG. 2 can contribute to afurther reduction in the mass moment of inertia. In principle, thisconstruction essentially corresponds to the embodiment form according toFIG. 1. However, it will be seen that the radial extension of thehousing hub 28 is appreciably reduced. Since the housing hub 28 isconstructed as a solid metal part, this represents a considerable savingof weight and a corresponding reduction in the mass moment of inertia.It will be seen in the embodiment form according to FIG. 1 thatapproximately half of the radial extension between the friction outerdiameter and the axis of rotation A is occupied by the housing hub 28,while in the embodiment form according to FIG. 2 this value is in therange of one third. In other respects, the embodiment form according toFIG. 2 corresponds to the preceding embodiment form described above withreference to FIG. 1, and reference is had to the preceding comments.

[0029] Of course, changes can be made in various areas of the torqueconverter according to the invention without diverging from theprinciples of the present invention. For example, the intermediatefriction element or intermediate friction elements could also be coupleddirectly with the piston 58 so as to be fixed with respect to rotationrelative to it. Also, the carrier elements 77, 78 of the frictionelements 66, 68 could be bent in their radial outer area toward theflywheel to enable a reduction in the axial extension of the drivingelement 80 away from the turbine wheel 32. The two carrier elements 77,78 could also be bent toward one another in their radial outer areas sothat the toothing arrangement of the driving element 80 can be reducedwith respect to its axial extension. If it is necessary to provide atorsional vibration damper for reasons pertaining to vibrations oroperation in various drive systems, this could be provided in the arearadially inside the lockup clutch arrangement essentially axiallybetween the clutch piston 58 and the turbine wheel shell 34, where thereis sufficient space available.

1. Hydrodynamic clutch device, particularly a torque converter or fluidclutch, comprising a housing arrangement (12), a turbine wheel (32)provided in the housing arrangement (12), a lockup clutch arrangement(56) by means of which a torque transmission connection can be producedselectively between the turbine wheel (32) and the housing arrangement(12), the lockup clutch arrangement (56) comprising at least onesubstantially annular friction element (66, 68) which is connected tothe turbine wheel (32) for rotating jointly about an axis of rotation(A) and a pressing element (58) which is connected to the housingarrangement (12) for joint rotation about the axis of rotation (A) andby means of which the at least one friction element (66, 68) can beacted upon to produce the torque transmission connection between turbinewheel (32) and housing arrangement (12), characterized in that a ratioof a flow outer diameter (a) in the area of the turbine wheel (32) to afriction outer diameter (b) of the at least one friction element (66,68) ranges between 1.30 and 1.80, preferably between 1.35 and 1.70,and/or in that a ratio of a friction outer diameter (b) of the at leastone friction element (66, 68) to a friction inner diameter (c) of the atleast one friction element (66, 68) ranges between 1.10 and 1.25,preferably between 1.15 and 1.20.
 2. Hydrodynamic clutch deviceaccording to claim 1, characterized in that, in an area radially outsideof the lockup clutch arrangement (56), the housing arrangement (12) hasa shape that is adapted to the outer circumferential contour of thelockup clutch arrangement (56) and to the outer circumferential contourof the turbine wheel (32).
 3. Hydrodynamic clutch device according toclaim 2, characterized in that the housing arrangement (12) isconstructed in a first housing portion (96) so as to surround the lockupclutch arrangement (56) substantially cylindrically and has, in a secondhousing portion (98) adjoining the first housing portion (96), a shapewhich is curved in direction of the axis of rotation (A) and extendsalong the outer circumferential area of the turbine wheel (32). 4.Hydrodynamic clutch device according to one of claims 1 to 3,characterized in that the at least one friction element (66, 68) isconnected to the turbine wheel (32) so as to be essentially rigidagainst rotation by a driving element (80).
 5. Hydrodynamic clutchdevice according to one of claims 1 to 4, characterized in that thepressing element (58) is connected to the housing arrangement (12) so asto rotate jointly by a driving arrangement (62, 64) which is arrangedessentially in the axial area between the pressing element (58) and theturbine wheel (32).
 6. Hydrodynamic clutch device according to one ofclaims 1 to 5, characterized in that a plurality of friction elements(66, 68) are provided, wherein an intermediate friction element (82)connected to the housing arrangement (12) for joint rotation is arrangedbetween each two friction elements (66, 68).
 7. Hydrodynamic clutchdevice according to one of claims 1 to 6, characterized by asubstantially annular first coupling element (102) which is connected inits radial inner area to an outer side of the housing arrangement (12),preferably by laser welding, and is constructed in its radial outer areafor coupling with a second coupling element which is fixedly connectedor connectable to a drive shaft.
 8. Hydrodynamic clutch device accordingto one of claims 1 to 7, characterized in that an interior space (20) ofthe housing arrangement (12) is divided by a pressing element (58) intoa first space (86) in which the turbine wheel (32) is arranged and asecond space (88), and in that work fluid can be introduced into thefirst space (86) and work fluid can be conducted out of the second space(88), or vice versa, for exchange of work fluid provided in the interior(20).
 9. Hydrodynamic clutch device according to claim 8, characterizedin that at least one fluid through-opening (94) is provided in thepressing element (58) to enable an exchange of fluid between the firstspace (86) and the second space (88).
 10. Hydrodynamic clutch deviceaccording to claim 8 or 9, characterized in that a flow channelarrangement which is preferably arc-shaped is provided in a frictionsurface region of the at least one friction element (66, 68).